Equilibrium Calculations
Introduction
- Types of Equilibrium Calculations:
- Calculation of an equilibrium constant
- Calculation of missing equilibrium concentration or partial pressure
- Calculation of equilibrium concentrations (or partial pressures) from initial concentrations (or partial pressures)
Manipulating Equilibrium Constants
- The equilibrium constant of a reaction in the reverse reaction is the reciprocal of the equilibrium constant of the forward reaction
- The equilibrium constant of a reaction that has been multiplied by a number is the equilibrium constant raised to a power that is equal to that number
- The equilibrium constant for a net reaction made up of two or more steps is the product of the equilibrium constants for the individual steps.
Solving Equilibrium Problems
- All equilibrium problems require the correct expression for K (or Q).
- They can be divided into 4 types. Two are very easy, the third more complicated, the fourth more complicated, but unfortunately, more common.
- All concentrations (or pressures ) are given, find K.
- Simply substitute the given values into the equilibrium expression.
- K is given. All but one of the equilibrium concentrations are given, find the other one.
- Finding K, when all the initial concentrations are known, and ONE equilibrium concentration is given.
- It is necessary to set up a reaction table, sometimes called an “ICE chart” to find ALL the equilibrium concentrations.
- THEN, you can put those values into the equilibrium equation to find K.
- K is known, initial conc. are known, find one or more FINAL concentration.